As is well known in the art, an electronic switching system (ESS) selectively connects two assigned subscribers so as to establish a communication line therebetween.
As shown in FIG. 1, the ESS 1 comprises a multiplicity of switching subsystems (SS's) 10 and an administration subsystem (AS) 20. In FIG. 1, for the sake of simplicity, it is provided only one SS 10 in the ESS 1. The SS 10 includes a call handling unit (CHU) 120 and a charge data generating unit (CGU) 110 to communicate information between two selected subscribers and generate charge data. The AS 20 coupled with the SS 10 controls all the operations and maintenance functions of the ESS 1, such as administering the charge data and the like. The AS 20 includes a charge data recording unit (CRU) 130, a disk unit (DKU) 140, a magnetic tape unit (MTU) 150, a charge data verifying unit (CVU) 160, and a verification database (VDB) 170.
When a call is terminated, predetermined details of the call, such as a type of call (e.g., long distance call), a type of subscriber (e.g., ISDN subscriber), a charge class (e.g., source charging), a source number, a destination number, a calling start time and a calling end time, are transferred from the CHU 120 to the CGU 110. The charge data for the call is generated to have a predetermined format and size based on the details of the call at the CGU 110 and transmitted to the CRU 130 of the AS 20.
And the transmitted charge data are assembled into a data block of a predetermined size (e.g., 1 Kbyte) at the CRU 130 to be recorded on the DKU 140 on a block-by-block basis. The data block includes a block header, a predetermined number of charge data and a checksum value. The recorded data blocks are transferred to the MTU 150 periodically with a predetermined time period or when the transfer of the charge data is requested.
A call billing for a subscriber is done based on the charge data stored at the MTU 150 and predetermined billing rates. It may occur that the subscriber argues his/her call billing. As the arguing subscriber requests charge data verifying process for his/her call, the subscriber is registered on the CGU 110 for charge data verification and then the charge data for the registered subscriber is transmitted from the CGU 110 to the CVU 160. The CVU 160 verifies the transmitted charge data, e.g., displays it on display and records it on the DB 170. And the charge data stored in the MTU 150 is analyzed to check whether or not there is any erroneous charge data.
However, in such an ESS 1, the CVU 160 is capable of verifying only the charge data whose verification is requested after the registration for the verification process. And also an error in the charge data is detected only after the charge data on the MTU 150 is analyzed. Consequently, it is desirable to analyze the charge data automatically (i.e., simultaneously with transferring the charge data from DKU 140 to the MTU 150) and use the analysis result to start the verification process or send an error message to an operator.
Hitherto, no prior art ESS is known to have such analyzing capabilities.